RUELLIA 



531 



tates with iodin or Mayer's reagent that are soluble in mineral acids; 

 a bitter, acrid principle; volatile oil; resin; tannin; and starch. 



Ruellia. For a number of years true Spigelia has been sub- 

 stituted by or admixed with the rhizome and roots of east Tennessee 

 pinkroot (Ruellia ciliosa), a perennial herb, belonging to the Acan- 

 thacese and growing in woods and thickets of the southern United 

 States. The rhizome is somewhat oblique, having the basal portions 

 of the aerial shoots usually attached. It is yellowish-brown, pos- 

 sessing a central pith and thick, hard wood. The roots are cylin- 

 drical and vary from yellowish-brown to dark brown, nearly straight, 

 somewhat wiry, the bark being easily detached, leaving the tough, 

 wiry, light yellowish wood exposed. 



-End. 



FIG. 227. Ruellia ciliosa, the rhizome and roots of which are a common adul- 

 terant of spigelia. A, transverse section of a secondary root: C, cortical 

 parenchyma with one cystolith and a number of stone cells with very thick 

 walls and radiating simple pores: End, endodermis. B, longitudinal section 

 of the same root, showing a single cell with an elongated cystolith, the en- 

 crustation being of calcium carbonate. After Holm. 



The histology of the rhizome of Ruellia is as follows: epidermal 

 cells, tangentially elongated, the outer walls being much thickened ; 

 outer cortical layer composed of parenchyma cells, having collen- 

 chymatous thickenings of the wall, and cystolith-containing cells; 

 inner cortical zone made up of thin-walled parenchyma, leptome and 

 sclereids or strongly lignified, elongated stone cells having thick, 

 porous and lamellated walls; endodermis distinct; xylem composed 

 of a compact zone of porous tracheae, and wood fibers ; pith consisting 



